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Search: id:A072542
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| A072542 |
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a(n) = the least positive integer k such that sigma(k) > sigma(1) + ... + sigma(n). |
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+0
1
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| 2, 4, 6, 10, 12, 18, 20, 24, 30, 36, 48, 60, 60, 60, 72, 84, 96, 108, 120, 120, 144, 168, 168, 180, 180, 210, 240, 240, 240, 288, 288, 300, 336, 336, 360, 360, 360, 420, 420, 420, 480, 480, 504, 540, 600, 600, 600, 660, 660, 720, 720, 720, 720, 840, 840, 840
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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sigma(1) + ... + sigma(4) = 15 and k = 10 is the least positive integer such that sigma(k) > 15. Hence a(4) = 10.
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MATHEMATICA
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s = 0; a = {}; For[i = 1, i <= 100, i++, s = s + DivisorSigma[1, i]; k = 1; While[DivisorSigma[1, k] <= s, k = k + 1]; a = Append[a, k]]; a
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CROSSREFS
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Sequence in context: A033098 A033868 A045954 this_sequence A162578 A152919 A092249
Adjacent sequences: A072539 A072540 A072541 this_sequence A072543 A072544 A072545
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KEYWORD
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nonn
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AUTHOR
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Joseph L. Pe (joseph_l_pe(AT)hotmail.com), Dec 08 2002
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